Apparatus and method for continuous filtering

ABSTRACT

A traveling filter comprising a plurality of trays disposed to travel along a path, a plurality of frames adapted to travel along a second path and through a portion of said path mate with the trays to confine material thereon, and a plurality of conduit means adapted to travel along a third path and adapted to be advanced and retracted to establish communication with and discharge liquid from said trays.

[451 Feb. 5, 1974 United States Patent [1 1 Eakins [56] References Cited UNITED STATES PATENTS APPARATUS AND METHOD FOR CONTINUOUS FILTERING [76] Inventor:

[22] Filed:

[21] Appl. No.: 354,151

2,677,467 5/1954 Giorgini.......................... 210/400 X 2,688,406

William S. Eakins, Glen Cove, NY.

19 4 40l Apr- 24 1973 9/ 5 Holland 210/ X Primary Examiner-John Adee Attorney, Agent, or FirmJohn Q. McQuillan Related US. Application Data ABSTRACT A traveling filter comprising a plurality of trays disposed to travel along a path, a plurality of frames adapted to travel along a second path and through a portion of said path mate with the trays to confine material thereon, and a plurality of conduit means adapted to travel along a third path and adapted to be advanced and retracted to establish communication with and discharge liquid from said trays.

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SHEET IISUF 17 PATENTED 74 SHEEI 170F 17 W V wuwtw APPARATUS AND METHOD FOR CONTINUOUS FILTERING This is a division, of application Ser. No. 160,746 filed July 8, 1971 which is a continuation-in-part of my copending application Ser. No. 845,984 filed July 30, 1969, now US. Pat. No. 3,615,01 1 application Ser. No. 845 ,984 being a division of my then copending application filed Dec. 21, 1966 which issued as US. Pat. No. 3,460,674, the last mentioned application being a continuation-in-part of my then co-pending application Ser. No. 578,361 filed Sept. 9, 1966.

This invention relates to continuous filtering and more in particular to a traveling filter in which vacuum is applied to the filter medium as it is conveyed.

In prior art continuous or traveling filters several different difficulties have commonly been encountered. One difficulty is that of applying a flow of fluid, whether it be induced by a pressure or a vacuum source, to the traveling filter in order to treat the filter cake being accumulated upon the filter medium. During and after the delivery of the material to be filtered to the filter medium which can be mounted upon a filter tray, it is generally necessary to apply a vacuum condition in order to draw the liquid portion of the material through the filter medium and thereby separate and build up a filter cake upon the medium. Since filtering apparatus commonly employs an endless belt of appreciable length of a plurality of traveling filter trays and since it is usually necessary to apply a vacuum or pressure condition to the belt or trays over an extensive period of travel, it becomes difficult to provide the necessary equipment for subjecting the belt or each of the filter trays at least through part of their travel throughout the apparatus to a vacuum or pressure condition without involving undue complexity or shortened life for the equipment.

In the prior art, vacuum has been applied to an endless belt or to the separate trays of a traveling filter by providing an elongated suction box over which the belt or trays are advanced. Since it is necessary to form a seal between the bottom portion of the belt or the trays and the suction box, the resulting arrangement is generally subject to excessive leakage and a comparatively high rate of wear between the fixed and stationary portions of the seal.

Another difficulty encountered with traveling filters has been that of obtaining an efficient, reliable and durable arrangement for removing the filter cake after its formation upon the filter medium. Wherever a plurality of continuously moving trays each having a filter medium are employed, difficulty is experienced in removing the filter cake from the tray since the cake tends to cling firmly to the tray and to the filter medium even though the tray is inverted after the formation of the filter cake. Where each tray is provided with side walls of sufficient height to receive and confine a substantial quantity of material to be filtered, the side walls of the tray present a greater area to which the filter cake can cling and adhere during attempts to remove the cake from the tray. Attempts to insure removal of the cake from the tray by the application of reverse blasts or jets of pressure fluid to the filter cake have also resulted in complicated designs which still fail to provide for the simple and reliable removal of the filter cake from the filter medium within the tray.

It is therefore one of the objects of the invention to provide a traveling filter to which a flow of pressured or vacuum fluid'can be applied without the need of continuously sliding seals or the like between the filter trays and the source of the flow of pressured or vacuum fluid.

It is another object of the invention to provide a traveling filter in which the duration of the applying of pressure or vacuum to the filter trays can be accurately controlled.

It is still another object of the invention to provide a traveling filter in which pressure or vacuum can be applied in a controlled manner with respect to each of the filter trays independently of one another.

It is an additional object of the invention to provide a traveling filter in which fluid can be applied with respect to each tray individually even though the filter travels over an appreciable distance.

It is a further object of the invention to provide a traveling filter in which the construction of the trays is conditioned to facilitate the release and the removal of the filter cake.

It is still a further object of the invention to provide a traveling filter in which the material to be filtered and the resulting filter cake is confined to the filter medium only during a portion of the travel of the tray.

It is another object of the invention to remove filter cakes from a traveling filter in a clean efficient manner.

It is another object of the invention to intermittently feed the trays of a traveling filter in sequential manner.

It is also an object of the invention to provide a traveling filter in which the filter medium of each of the trays can be operated to facilitate the removal of the filter cake therefrom.

In one of the embodiments of the invention the traveling filter includes a plurality of tray members each having a filter medium which is adapted to receive material to be filtered. Each of the plurality of tray members has a passage for passing a flow of fluid with respect to the tray member. Means are provided for conveying the plurality of tray members along a predetermined path. At least one conduit adapted to be connected to a device for producing a flow of fluid is provided. In addition, means are provided for driving the conduit along an additional path adjacent to at least a portion of the predetermined path of the tray members. Means are also provided for successively advancing and retracting the conduit with respect to its additional path as the conduit is driven in order successively to engage and disengage the conduit with respect to the passage of the tray member as the tray member is conveyed.

An advantage of this arrangement is that the operation of the conduit can be conveniently established at various locations along the predetermined path of the tray members since the conduit is driven adjacent to the path of the tray members and since the conduit is advanced and retracted with respect to its own path. An additional advantage is that it enables a flow of fluid to be controlled with respect to each individual tray member independently of the remaining tray members. Another advantage is that the advancing and retracting of the conduit enables the passage of the tray member to be engaged and disengaged at various locations along its predetermined path of travel without interfering with the conveying of the tray member.

In another embodiment of the invention the tray members are provided with a cavity with which the passage is in communication and over which the filter meto successively engage and disengage the passage of the tray member in order to establish a flow of fluid with respect to the tray member.

In a further embodiment of the invention the traveling filter comprises a plurality of tray members each having a filter medium and means for conveying the tray members along a predetermined path. The filter further includes a plurality of frame members each having an opening adapted to mate in a facing relationship with the surface area of the filter medium. Means are provided for moving the plurality of frame members along another path extending at least in part adjacent to the predetermined path of the tray members in order successively to place and remove the opening of each of a portion of the plurality of frame members with respect to a condition of registry and substantial engagement with a different one of the tray members ofa corresponding portion of the plurality of tray members.

An advantage of this arrangement is that the frame members are adapted to confine the material to be filtered upon the filter medium adjacent thereto. Subsequently, upon removal of the frame members from in registry and substantial engagement with the tray members, the removal of the filter cakes from the filter mediums is facilitated and made more positive.

In still a further embodiment of the invention the conveying means for the plurality of tray members and the plurality of frame members each have upper and lower reaches with at least a portion of the lower reach of the frame members overlying and sufficiently adjacent to the upper reach of the tray members in order to enable the frame members to be placed in registry and substantial engagement with the tray members.

In another embodiment of the invention the traveling filter includes means for delivering the material to be filtered through the openings of the frame members as the frame members are moved along the lower reach of their conveying means.

In another embodiment, a hopper is positioned within the reach of the conveying means to be filled with feed material and intermittently pivoted in response to the presence of a tray underneath to dump its contents into successive trays.

In a still further embodiment of the invention, the traveling filter has a take-up roller mounted adjacent a conveying means and a pair of scrapper blades. The take-up roller is provided with ports in the surface which communicate with a vacuum source to hold the cake material and the blades are arranged so that one scrapes a filter cake onto the roller and the other scrapes an upper layer of cake material from the roller at an advanced position.

Various other objects and advantages of the present invention will be readily apparent from the following detailed description when considered in connection with the accompanying drawings in which:

FIG. 1 is an elevational view of the traveling filter of the invention showing the lower reach of the conveyor of the frame members overlying and in substantial engagement with the upper reach of the conveyor of the tray members with means for successively advancing and retracting the conduits disposed adjacent to the upper reach of the conveyor for the tray members;

FIG. 2 is a fragmentary elevational view of the traveling filer showing the means for driving the conduits along an additional path adjacent to a portion of the predetermined path of the tray members;

FIG. 3 is a fragmentary plan view of the conveyor for the tray members showing the conduits and the means for driving the conduits along an additional path adjacent to a portion of the predetermined path of the conveyor of the tray members;

FIG. 4 is a plan view of a single one of the assemblies of conduits with the means for successively advancing and retracting the conduits as they are driven with respect to the conveyor for the tray members;

FIG. 5 is a vertical section view taken along the line 5-5 in FIG. 4 and showing the control valve arrangement for the flow of fluid through the conduits;

FIG. 6 is a vertical section view taken along the line 66 of FIG. 5 and showing the means for driving the conduits along an additional path adjacent to the predetermined path of the tray members;

FIG. 7 is a perspective view of one of the plurality of tray members and one of the plurality of frame members in registry and substantially engaged with the tray member;

FIG. 8 is a vertical section view taken along a plane extending parallel to the line of travel of the tray member and showing the cavity, the filter medium and the passage of the tray member;

FIG. 9 is a plan view of one of the tray members showing the filter medium overlying the plate of the tray member;

FIG. 10 is an elevational view of the end portion of a passage connected to a tray member showing the alternate titled portions which the passage can assume with respect to its support;

FIG. 11 is a vertical section view taken along the line 11-11 in FIG. 8 and showing the passage and the valve connected thereto for a tray member in alignment with the conduit;

FIG. 12 is a fragmentary vertical section view showing the opening of a conduit advancing into engagement with the valve of the passage leading to the tray member;

FIG. 13 is a fragmentary vertical section view showing the opening of the conduit fully engaged with the open valve of the passage leading to the tray member;

FIG. 14 is a fragmentary vertical section view of the conveyors for the frame members and the tray members and showing the filter cake being released from the tray member after removal of the frame member;

FIG. 15 is a fragmentary vertical section view showing a detachable filter medium for facilitating the removal of the filter cake;

FIG. 16 is a fragmentary vertical section view showing means for assisting in the removal of the filter cake from the detachable filter medium; 

2. An apparatus in accordance with claim 1 in which said conveying means advances said tray members along upper and lower reaches corresponding to the first and second lines of travel, said filter medium being attached to the end portions of said opposite end portions of said tray member which is toward the direction of travel of said conveying means, whereby said weighted member is free to fall and swing said filter member with respect to said tray member as said tray member passes from said upper to said lower reach.
 3. A method of separating a filter cake from a filter medium disposed upon a tray member comprising the steps of conveying the tray member along a first line of travel upon which the tray member is erected, the filter medium being movably attached to the tray member, directing material to be filtered toward the filter medium of the trAy member as it is conveyed along the first line of travel, and conveying the tray member along a second line of travel upon which the tray member is at least in a partially inverted position, whereby the conveying of the tray member from an erected position on the first line of travel to at least a partially inverted position on the second line of travel causes the filter medium to move with respect to the tray member and thereby assist the release of the filter cake from the filter medium.
 4. A method in accordance with claim 3 in which the filter medium swingably attached to the tray member and in which the step of conveying the tray member in an inverted position along a second line of travel causes the filter medium to swing about its swingable attachment to the tray member and thereby assist the release of the filter cake from the filter medium.
 5. Apparatus for removing filter cake from the filter medium of a stationary filter comprising a porous roller mounted to a frame member, said frame member being adapted to move said porous roller along a predetermined path, said filter to be mounted adjacent said path of movement of said porous roller with a portion of said roller being at a substantially close clearance with said filter medium of said filter, means for rotating said roller with the peripheral movement of said portion of said roller being in the opposite direction as the movement of said roller, an additional filter medium disposed upon said porous roller, means for inducing fluid flow through said additional filter medium into said porous roller, the fluid flow forming an additional filter cake upon said roller from the filter cake on said filter medium, the additional filter cake engaging the filter cake on said filter medium, and a scraper blade disposed adjacent said roller for scraping a layer of filtered material from said roller to retain a uniform layer of additional filter cake thereon and to remove the remainder of filtered material therefrom, whereby the engagement of the additional filter cake on said roller with the filter cake on said filter medium enables the filter cake on said filter medium to be removed.
 6. An apparatus in accordance with claim 5 further comprising means for moving said porous roller along said predetermined path.
 7. An apparatus in accordance with claim 5 further comprising an additional scraper blade disposed adjacent to the surface of said filter members downstream of said roller, said additional scraper blade extending adjacent to the periphery of said roller and to a substantially close clearance with respect to the surface of said filter members, whereby said additional scraper blade assists in the removal of the filter cake.
 8. An apparatus in accordance with claim 5 and further comprising means for pivotally mounting said porous roller and said scraper, means for biasing said mounting means toward said filter medium, and means for engaging said mounting means to limit the clearance between said roller and said filter medium.
 9. Method of removing filter cake from the filter medium of a stationary filter comprising moving a porous roller having an additional filter medium disposed thereupon along a predetermined path, mounting and filter adjacent said path of movement of said porous roller with a portion of said roller being at a substantially close clearance with said filter medium of said filter, rotating said roller with said peripheral movement of said portion of said roller being in the opposite direction as the movement of said roller, inducing fluid flow through said additional filter medium into said porous roller, the fluid flow forming an additional filter cake upon said roller from the filter cake on said filter medium, the additional filter cake engaging the filter cake on said filter medium, and scraping a layer of filtered material from said roller to retain a uniform layer of additional filter cake thereon and to remove the remainder of filtered material therefrom, whereby the engagemenT of the additional filter cake on said roller with the filter cake on said filter medium enables the filter cake on said filter medium to be removed.
 10. A method in accordance with claim 9 and further comprising the additional step of scraping the filter cake from the filter medium downstream of the roller and adjacent thereto.
 11. A traveling filter comprising a plurality of tray members each having a filter medium disposed thereupon, means for conveying said plurality of tray members along a predetermined path, a plurality of spaced apart frame members each of which has an opening adapted to mate in a facing and sealing relationship with the surface area of said filter medium, means for moving said plurality of frame members along another path extending at least in part adjacent to said predetermined path in order successively to place and remove the opening of each of a portion of said plurality of frame members with respect to a condition of registry and sealing engagement with a different one of said tray members of a corresponding portion of said plurality of tray members, said frame members being adapted to confine a material to be filtered upon said filter mediums when said frame members are placed in registry and sealing engagement with said tray members, removal of said frame members from registry and sealing engagement with said tray members facilitating the removal of filter cakes from said filter media, means for continuously delivering material to be filtered through the openings of said frame members as said frame members are moved along said other path, said material to be delivered to one side of said filter media, means advancing in synchronism with the frame members for directing the continuously delivered material through at least one of the openings of said adjacent frame members as the space therebetween moves adjacent the material delivery means for preventing said material from entering said space, and means for removing filtrate from the opposite side of said filter media thereby forming a filter cake on the one side of said filter media.
 12. An apparatus in accordance with claim 11 in which said material directing means comprises a plurality of guard members mounted for movement with said frame members, one guard member being disposed adjacent the space between said adjacent frame members, said guard member adapted for directing the continuously delivered material through at least one of the openings of adjacent frame members as the space therebetween moves adjacent the material delivered means and for preventing said material from entering said space.
 13. An apparatus in accordance with claim 12 in which each of said frame members has at least four walls defining the opening, one of the walls of each frame member being parallel to one of the walls of each of said adjacent frame members, and in which each guard member comprises a channel member extending substantially the length of the space between said adjacent frame members with the longitudinal axis thereof substantially parallel to the adjacent walls of said adjacent frame members, the open portion of said channel member extending towards said adjacent frame members for directing said continuously delivered material which impacts said channel member away from said space and through at least one of said openings of adjacent frame members.
 14. An apparatus in accordance with claim 13 in which said channel member is a ''''V''''-shaped member.
 15. An apparatus in accordance with claim 13 and further comprising a porous roller mounted adjacent said predetermined path and at a substantially close clearance with respect to the surface of said filter mediums of said tray members downstream of said material delivery means, means for rotating said roller with the peripheral movement thereof being in the same direction as the movement of said filter media, an additional filter medium disposed upon said porous roller, means for inducing fluid flow through said additional filter medium into said porous roller, the fluid flow forming an additional filter cake upon said roller from the filter cake on said filter mediums of said members, the additional filter cake engaging the filter cake on said filter mediums of said tray members, and a scraper blade disposed adjacent said roller for scraping a layer of filtered material from said roller to retain a uniform layer of additional filter cake thereon and to remove the remainder of filtered material therefrom, whereby the engagement of the additional filter cake on said roller with the filter cake on said filter members enables the filter cake on said filter mediums of said tray members to be removed.
 16. A method of filtering a material to form filter cakes on a filter medium comprising the steps of conveying a plurality of tray members each having a filter medium disposed thereon along a predetermined path having at least a first portion and a second portion, and moving a plurality of frame members each of which has an opening adapted to mate in a facing relationship with the surface area of said filter medium along another path extending at least in part adjacent to said first portion of said predetermined path in order to successively place the opening of each frame member of a portion of said plurality of frame members in a condition of registry and substantial engagement with a different one of said tray members of a corresponding portion of said plurality of tray members adjacent one end of said first portion of said predetermined path and to remove the opening of each of said frame members from said condition of registry and substantial engagement at the other end of said first portion of said predetermined path, the moving of said frame members into a condition of registry and substantial engagement with said frame members enabling said material to be confined upon said filter mediums of said tray members, said filter cakes being adapted to be processed as said filter cakes move along said second portion of said predetermined path.
 17. A method of filtering in accordance with claim 16 and further including the step of producing said filter cakes as said filter cakes move along said second portion of said predetermined path.
 18. A method in accordance with claim 17 in which said step of processing said filter cakes comprises applying heat to said filter cakes to reduce the moisture content thereof as said filter cakes move along said second portion of said predetermined path.
 19. A method of filtering in accordance with claim 16 in which the plurality of tray members are conveyed along a predetermined path which includes upper and lower reaches, said upper reach including said first portion and said second portion of said predetermined path, and in which the plurality of tray members are moved along another path extending at least in part adjacent to said first portion of said predetermined path which includes upper and lower reaches with at least a portion of the lower reach thereof overlying and sufficiently adjacent to said first portion of said upper reach of said conveying means to enable said frame members to be placed in registry and substantial engagement with said tray members.
 20. A method of filtering in accordance with claim 18 in which the step of applying heat to said filter cakes includes passing a hot gas across said filter cakes.
 21. A traveling filter for filtering a material to form filter cakes on a filter medium comprising a plurality of tray members each having a filter medium disposed thereon, means for conveying said plurality of tray members along a predetermined path having at least a first portion and a second portion, a plurality of tray members each of which has an opening adapted to mate in a facing relationship with the surface area of said filter medium, and means for moving said plurality of frame members along another path extending at least in part adjacent to said first portion of said predetermined path in order successively to place and remove the Openings of each frame member of a portion of said plurality of frame members with respect to a condition for registry and substantial engagement with a different one of said tray members of a corresponding portion of said plurality of said tray members, said frame members being adapted to confine said material to be filtered upon said filter mediums when said frame members are placed in a condition of registry and substantial engagement with said filter mediums, said filter cakes being adapted to be processed as said filter cakes move along said second portion of said predetermined path.
 22. A traveling filter in accordance with claim 21 further including means for processing said filter cakes as said filter cakes move along said second portion of said predetermined path.
 23. A traveling filter in accordance with claim 22 in which said processing means comprises a means for applying heat to said filter cakes to reduce the moisture content thereof as said filter cakes move along said second portion of said predetermined path.
 24. A traveling filter in accordance with claim 21 in which said means for conveying said plurality of tray members along a predetermined path includes a path having upper and lower reaches, said upper reach including said first portion and said second portion of said predetermined path, and in which said means for moving said plurality of frame members along another path extending at least in part adjacent to said first portion of said predetermined path includes another path having upper and lower reaches with at least a portion of said lower reach thereof overlying and sufficiently adjacent to said first portion of said upper reach of said conveying means to enable said frame members to be placed in a condition of registry and substantial engagement with said tray members.
 25. A traveling filter in accordance with claim 23 in which said means for applying heat to said filter cakes comprises a means for passing a hot gas across said filter cakes.
 26. A traveling filter in accordance with claim 22 in which said means for processing said filter cakes comprises a hood assembly mounted above and adjacent said tray members moving along said second portion of said predetermined path, said hood assembly being adapted to confine a processing fluid to be passed across said filter cakes adjacent said filter cakes as they pass beneath the hood assembly.
 27. A traveling filter in accordance with claim 26 in which said processing fluid is a hot gas and further including a means for providing hot gas to said hood assembly.
 28. A traveling filter in accordance with claim 27 in which said means for providing hot gas to said hood assembly comprising a furnace for heating said gas, a blower adapted to drive said heated gas from said furnace to said hood assembly, and a means for ducting said hot gas from said furnace to said hood assembly.
 29. A traveling filter in accordance with claim 22 in which each tray member of said plurality of tray members has structure forming a passage for passing a processing fluid adjacent said filter medium, said structure including a valve means communicatively connected to said passage, and in which said means for processing said filter cakes comprises at least one conduit, one end of said conduit being adapted to be connected to a device for producing a flow of a processing fluid therethrough and the other end of said conduit being adapted to be engaged and disengaged with said valve means, means for driving said conduit along an additional path adjacent to at least a portion of said second portion of said predetermined path, and a means for successively advancing and retracting said conduit with respect to said additional path as said conduit is driven in order to successively engage and disengage said conduit with respect to said valve means of said tray member as said tray member is conveyed along said second portion of said predetermined path, whereby said filter cakes are processed by the flow of the processing flUid through said filter medium and adjacent said filter cake when said conduit engages said valve means of said tray member.
 30. A traveling filter in accordance with claim 29 in which said processing fluid is a hot gas for applying heat to said filter cakes.
 31. A traveling filter in accordance with claim 29 in which said means for driving said conduit along an additional path adjacent to at least a portion of said predetermined path comprises an endless drive coupled to said conduit and having a portion moving parallel to said predetermined path, said conduit extending at substantially right angles to said predetermined path, and in which said means for successively advancing and retracting said conduit with respect to said additional path comprises means responsive to the movement of said endless drive for successively feeding and withdrawing said conduit along the longitudinal axis thereof with respect to the passage of said tray member.
 32. A traveling filter in accordance with claim 29 and further comprising means in circuit with said conduit for controlling the flow of said processing fluid therethrough, said controlling means being responsive to the movement of said conduit along said additional path adjacent to at least a portion of said predetermined path.
 33. A traveling filter in accordance with claim 29 in which each of said tray members have structure forming a plurality of said passage for passing a flow of said processing fluid adjacent said filter medium, in which there is a plurality of said conduit adapted to be connected to a device for producing a flow of said processing fluid therethrough, and in which said conduit advancing and retracting means successively engages and disengages said plurality of conduits with respect to said plurality of passages of said tray member as said tray member is conveyed.
 34. A traveling filter in accordance with claim 25 in which each tray member of said plurality of tray members has structure forming a passage for inducing a flow of hot gas through said filter cake, said structure including a valve means communicatively connected to said passage, and further comprising at least one conduit, one end of said conduit being adapted to be connected to a device for inducing a flow of a hot gas from said hot gas passing means through said filter cake and the other end of said conduit being adapted to be engaged and disengaged with said valve means, means for driving said conduit along an additional path adjacent to at least a portion of said second portion of said predetermined path, and a means for successively advancing and retracting said conduit with respect to said additional path as said conduit is driven in order to successively engage and disengage said conduit with respect to said valve means of said tray member as said tray member is conveyed along said second portion of said predetermined path, whereby the moisture content of said filter cake is reduced by the flow of the hot gas through said filter cake when said conduit engages said valve means of said tray member. 